Skin Care I & II: Sunscreen and Sun Tan Products

Flashcards covering the properties of UV radiation, skin tanning processes, types of sunscreens, SPF/PPD measurements, and application guidelines.

What is the range of the Ultraviolet (UV) radiation spectrum?

The UV spectrum ranges from $200-400\,nm$.

Into which three bands is the UV spectrum divided?

The spectrum is divided into UVC, UVB, and UVA.

What is the wavelength range of the UVC band?

The UVC band ranges from $200-290\,nm$.

Why does little UVC radiation reach the surface of the earth?

It is screened out by the ozone layer of the upper atmosphere.

By which skin layer is artificial UVC radiation (e.g., from mercury lamps) absorbed?

It is absorbed by the dead cell layer of the epidermis.

What are the primary effects of UVC radiation on the skin?

UVC does not stimulate tanning, but it causes some redness of the skin.

What is the wavelength range of the UVB band?

The UVB band ranges from $290-320\,nm$.

What is the common name for UVB radiation?

It is also called the sunburn radiation.

Which UV band causes the usual sunburn reaction and stimulates a slow tan?

The UVB band.

Which UV band is considered the most erythrogenic and melanogenic?

The UVB band.

What beneficial substance requires small amounts of UVB for synthesis in the skin?

Vitamin D.

What is the wavelength range of the UVA band?

The UVA band ranges from $320-400\,nm$.

How much more UVA reaches the earth's surface compared to UVB?

UVA reaches the surface in $10-100$ times the amount of UVB.

Why can UVA protection not be measured in standard SPF testing?

UVA penetrates deeply but does not cause sunburn, which is what SPF measures.

Which UV band is often used in tanning booths to give a quick tan?

The UVA band.

What skin conditions are attributed to UVA radiation?

Photosensitivity reactions, photoaging, and photodermatoses.

How does UVA indirectly cause DNA damage?

Via free radicals and reactive oxygen species (ROS).

What percentage of the cells at the bottom layer of the epidermis are melanocytes?

About $8\%$.

What is the primary function of melanocytes?

They are specialized cells that synthesize melanin.

How is melanin distributed once it is formed by melanocytes?

It is passed on to keratinocytes, which ingest the melanin pigments.

How does melanin protect underlying tissues from UV radiation?

It forms a pigment shield that absorbs UV radiation and dissipates the energy as heat.

What are the two protective mechanisms triggered by UV radiation in the skin?

Increased melanin production by melanocytes and the oxidation of existing melanin.

What does the acronym IPD stand for in the context of tanning?

Immediate pigment darkening.

What is the term for the 'delayed tanning' process that follows IPD?

Melanogenesis.

What are three types of skin cancer associated with UVR exposure?

Squamous cell carcinoma, basal cell carcinoma, and malignant melanoma.

At what time of day is the exposure to harmful UVB rays the greatest?

Between $10\,am$ and $2\,pm$.

What percentage of UV rays reaching the earth's surface are UVA?

UVA rays make up $95\%$ of rays reaching the surface.

What percentage of UVR can penetrate through cloud layers?

Cloud layers allow $60-80\%$ of UVR penetration.

By what percentage does UVB intensity increase with altitude?

UVB intensity increases $4\%$ with each $1000$-foot increase in altitude.

Which individuals are at the greatest risk for sunburn and skin damage?

People with fair skin and light hair.

What are the two basic types of sunscreen agents?

Physical and Chemical.

How much light do physical sun blocks reflect and scatter?

They reflect and scatter up to $99\%$ of light in both UV and visible spectrums.

What is the wavelength spectrum blocked by physical sun blocks?

$290-700\,nm$.

What are two common examples of physical sun block ingredients?

Titanium Dioxide and Zinc Oxide.

What is one major advantage of physical sun blocks regarding timing?

They protect immediately after application.

Why might physical sun blocks be less cosmetically acceptable?

They have a greasy appearance and may leave a white-ish cast on the skin.

What occurs more frequently when sweating while wearing physical sun block?

White drips may show on the skin.

What is the primary mechanism of chemical sunscreens?

They absorb a specific portion of the UV light spectrum to prevent skin penetration.

How many main groups of chemical sunscreens are available?

There are $5$ main groups.

What is an advantage of chemical sunscreens regarding their texture?

They tend to be thinner and spread more easily on the skin.

How long after application does a chemical sunscreen begin to work?

It requires about $20\,minutes$ before it begins to work.

What is the spectrum of Benzophenones like Oxybenzone?

They cover both UVA and UVB across $270-350\,nm$.

Which UV band do PABA and PABA esters primarily block?

The UVB band ($260-313\,nm$ upwards to $330\,nm$).

What is the spectrum range of Cinnamates like Octocrylene?

They block UVB across $250-360\,nm$.

What is the spectrum range of Salicylates like Homosalate?

They block UVB across $280-320\,nm$.

Which specific chemical sunscreen agent is used for UVA protection ($320-400\,nm$)?

Avobenzone (butyl methoxy-dibenzoylmethane).

Which ingredient provides broad protection from $290-700\,nm$?

Titanium dioxide or Zinc Oxide.

What does the acronym SPF stand for?

Sun Protection Factor.

What is the only currently accepted FDA marker for a sunscreen's protective ability?

SPF.

Which specific type of UV radiation does SPF measure?

Only UVB rays.

What is the formula for calculating SPF?

$$SPF = \frac{\text{MED (protected)}}{\text{MED (unprotected)}}$$

What does the acronym MED stand for?

Minimal Erythemal Dose.

How is MED defined?

Minimal sun exposure required to generate redness.

Calculate the theoretical protection time for an individual with an SPF 30 product who normally burns in 10 minutes.

$30 \times 10 = 300\,minutes$.

Why is the theoretical protection time of SPF products often inaccurate?

Sunscreen is easily removed, and reapplication every $2\,hours$ is recommended.

What does the acronym PPD stand for?

Persistent Pigmentation Darkening.

What is the purpose of the PPD method?

To evaluate a sunscreen product's protective ability in the UVA range.

What is the formula for calculating the UVA Protection Factor using PPD?

$$\text{UVA PF} = \frac{\text{MPD (Protected)}}{\text{MPD (Unprotected)}}$$

What does the acronym MPD stand for?

Minimal Pigmenting Dose.

What is one reason the FDA does not accept the PPD method?

The UVA light source used may not accurately represent natural UVA radiation.

Which rating system is derived from the PPD method in Japan?

The PA rating system.

In the Japanese system, what PPD protection factor range corresponds to PA+?

$2$ to less than $4$.

In the Japanese system, what PPD protection factor range corresponds to PA++?

$4$ to less than $8$.

In the Japanese system, what PPD protection factor value corresponds to PA+++?

Greater than or equal to ($\geq$) $8$.

Does the absence of a 'PA' label mean a product provides no UVA protection?

No, one must check the active ingredients or the rest of the label.

What are the characteristics of Skin Type I?

Always burn easily, never tans, particularly light skin, freckles, reddish hair.

What is the recommended SPF for Skin Type I according to selection guidelines?

$15$ or more.

Which skin type is described as 'Burns moderately; tans gradually'?

Skin Type III.

What is the recommended SPF for Skin Type II individuals?

$8-14$.

What are the characteristics of Skin Type VI?

Never burns, deeply pigmented.

What is the recommended SPF and PA for extreme sports like skiing or hiking?

SPF $30-50$ and PA+++.

Why do clouds provide a 'false sense of security' against UV radiation?

Clouds filter IR radiation (heat) but allow $60-80\%$ of UV radiation to penetrate.

What percentage of UV radiation can penetrate water to reach a submerged swimmer?

$95\%$.

What percentage of UV radiation is transmitted through wet clothes?

$50\%$.

What is the standard amount of sunscreen that should be applied to the skin?

$\approx 2\,mg/cm^2$.

How many 'portions' of sunscreen should an average adult in a bathing suit apply?

Nine portions.

What is the volume measurement of one 'portion' of sunscreen for application?

$\frac{1}{2}\,teaspoon$.

How many portions of sunscreen are designated for the legs and top of feet?

$2$ portions for each side ($4$ total).

Which body areas are covered by the 'Torso' portions of sunscreen?

One portion for the front and one for the back.

What does a 'Water Resistant' label signify on a sunscreen?

The product retains its SPF after $40\,minutes$ of activity in water or sweating.

What does a 'Very Water Resistant' label signify on a sunscreen?

The product retains its SPF after $80\,minutes$ of activity in water or sweating.

How long before sun exposure should sunscreen be applied for optimum action?

$30\,minutes$ before exposure.

At what age is it generally acceptable to start using sunscreen on infants?

Sunscreen should not be used on infants less than $6\,months$ of age.

What is the minimum recommended SPF for children under 2 years old?

SPF $4$.

Which chemical sunscreen agents are most likely to cause photosensitivity and contact dermatitis?

PABA and its esters.

What should a patient do if signs of irritation or rash occur while using sunscreen?

Discontinue use of the product.

How are sun tan products without sunscreen identified?

They are identified by the absence of an SPF value on the label.

What is a common feature of the formulation of sun tan products with sunscreen?

They use an oily vehicle that concentrates UV radiation onto the skin.

What is the FDA required warning on products that do not contain sunscreen?

That the product does not protect against sunburn and repeated exposure increases the risk of skin aging and skin cancer.

Which UV band causes 'indirect DNA damage' via reactive oxygen species (ROS)?

The UVA band.

Which UV ray has the longest wavelength in the radiation spectrum mentioned?

UVA ($400\,nm$).

Which UV ray is the most dangerous but mostly blocked by the ozone layer?

UVC.

What is the primary substance synthesized by melanocytes to protect skin?

Melanin.

Which cells in the epidermis 'shield' the skin by ingesting melanin?

Keratinocytes.

What is the peak period for damaging UVB radiation as per patient education?

Between $10\,am$ and $2\,pm$.

Is Skin Type V considered sensitive or insensitive to the sun?

Insensitive (rarely burns; tans profusely).

What is the genetic origin of Skin Type II?

Caucasian.

What is a common disadvantage shared by chemical sunscreens?

Increased chance of irritation and stinging due to multiple combined ingredients.

What is the spectrum range of Ethylhexyl salicylate?

$280-320\,nm$ (UVB).

Why are Zinc Oxide and Titanium dioxide called physical blocks?

Because they physically reflect and scatter light rather than absorbing it.